Evidence for nesting driven charge density waves instabilities in a quasi-two-dimensional material: LaAgSb2

Abstract

Since their theoretical prediction by Peierls in the 30s, charge density waves (CDW) have been one of the most commonly encountered electronic phases in low dimensional metallic systems. The instability mechanism originally proposed combines Fermi surface nesting and electron-phonon coupling but is, strictly speaking, only valid in one dimension. In higher dimensions, its relevance is questionable as sharp maxima in the static electronic susceptibility χ(q) are smeared out, and are, in many cases, unable to account for the periodicity of the observed charge modulations. Here, we investigate the quasi twodimensional LaAgSb2, which exhibits two CDW transitions, by a combination of diffuse xray scattering, inelastic x-ray scattering and ab initio calculations. We demonstrate that the CDW formation is driven by phonons softening. The corresponding Kohn anomalies are visualized in 3D through the momentum distribution of the x-ray diffuse scattering intensity. We show that they can be quantitatively accounted for by considering the electronic susceptibility calculated from a Dirac-like band, weighted by anisotropic electron-phonon coupling. This remarkable agreement sheds new light on the importance of Fermi surface nesting in CDW formation.

20 pages, 9 figures, submitted to Phys. Rev. Rep

References in corpus (7)

• Fermi surface nesting and the origin of Charge Density Waves in metals
• Classification of Charge Density Waves Based on Their Nature
• Origin of superconductivity and latent charge density wave in NbS${}_2$
• Alternative route to charge density wave formation in multiband systems
• Charge Order from Orbital-dependent Coupling Evidenced by NbSe${}_2$
• Giant Kohn anomaly and the phase transition in charge density wave ZrTe_3
• Revealing extremely low energy amplitude modes in the charge-density-wave compound LaAgSb${}_2$

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• Electron-momentum dependence of electron-phonon coupling underlies dramatic phonon renormalization in YNi${}_2$B${}_2$C
• Magnetotransport studies of the Sb square-net compound LaAgSb${}_2$ under high pressure and rotating magnetic fields
• Coexistence of Dirac fermion and charge density wave in square-net-based semimetal LaAuSb2
• Hybridization of lattice and charge order excitations in a superconducting cuprate
• NMR evidence for a Peierls transition in the layered square-net compound LaAgSb${}_2$
• Doping Tunable CDW Phase Transition in Bulk 1T-ZrSe${}_2$
• Dirac Dispersions and Fermi Surface Nesting in LaCuSb${}_2$
• Charge density waves and soft phonon evolution in the superconductor BaNi${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Interplay of Kondo Physics with Incommensurate Charge Density Waves in CeTe${}_3$